Antibronzing agents for photographic silver images

ABSTRACT

Antibronzing agents for silver images dried at high temperatures, which agents have 1,3,4-triazole-3-mercaptan rings bridged together at their 5-positions by an interrupted hydrocarbon linkage.

United States Patent von Kiinig et al. 51 Mar. 7, 1972 [54] ANTIBRONZING AGENTS FOR [58] Field of Search ..96/52, 67, 61, 66

PHOTOGRAPHIC SILVER IMAGES [56] References Cited [72] Inventors: Anita von Kiinig, Leverkusen; Helmut Timmler, Wuppertal-Vohwinkel, both of UNITED STATES PATENTS Gemmy 2,514,650 7/1950 Knott ..96/52 [73] Assignee: Agfa-Gevaert Aktiengesellschaft, Lever- 3,438,777 4/1969 Willems ..96/52 kusen, Germany Primary ExaminerNorman G. Torchin [22] 1969 Assistant Examiner-Mary F. Kelley [21] A l. M 809,415 Attorney-Connolly and Hutz [57] ABSTRACT [30] Foreign Application Priority Data l 5 Antlbronzlng agents for silver images dried at high tempera- Mar. 28, 1968 Germany ..P 17 70 074.2 tures, which agents have |34 triazo|e 3 mercaptan rings bridged together at their 5-positions by an interrupted [521 US. Cl ..96/52, 96/61, 96/66, hydrocarbon 1inkage 96/67 [51] Int. Cl ..G03c 7/00, G03c 5/38, G03c 1/76 8 Claims, No Drawings ANTIBRONZING AGENTS FOR PHOTOGRAPHIC SILVER IMAGES The invention relates to a process for the production of photographic images which includes drying on a high-gloss press at high temperature in effective contact with antibronzing agents of the bis-mercapto triazole series.

The silver images obtained from light-sensitive silver halide emulsion layers often undergo changes during high-gloss drying or during mechanical drying at high temperature. Thus commonly a loss in density occurs or blue-black image tones change to brownish tones and brown tones change into greenish black tones. These changes are known as partial burning" or bronzing of the silver image.

The incorporation of small quantities of certain chemical compounds, known as antibronzing agents, into the light-sensitive material which contains a silver halide emulsion copying layer is known. These compounds alternatively may be added to the treatment baths which are used for the material to prevent this loss of density.

The known antibronzing compounds are however, only of limited utility either because their antibronzing effect is not sufficient or because they impair the photographic properties.

it is among the objects of the present invention to provide new antibronzing agents which have a sufficiently large antibronzing effect and which do not deleteriously effect the photographic properties of the material.

We now have found that heteroalkylene-5,5-bis-l,2,4- triazole-3-mercaptans of the following formula are outstanding antibronzing agents.

in which R represents (1) hydrogen, (2) a saturated or olefinically unsaturated aliphatic group having l-l 8 carbon atoms and preferably one to six carbon atoms, (3) aryl such as a phenyl or naphthyl particularly a radical of the phenyl series, (4) aralkyl such as a benzyl or phenylethyl group, (5) cycloalkyl, such as a cyclohexyl group or (6) an amino group; these hydrocarbon radicals may also be substituted, e.g., with halogen, methyl, methoxy, hydroxyl, sulfo or carboxy groups;

X stands for a hydrocarbon chain such as alkylene, arylene, for example phenylene, or cycloalkylene. Preferred are aliphatic chains having 2-10 methylene groups in particular aliphatic chains which are interrupted by one or more preferably one to three heteroatoms such as oxygen, sulfur or imino or sulfonyl groups.

The above formula includes compounds in the tautomeric 3-thione form.

Examples of suitable compounds are shown in the following table:

The preparation of heteroalkylene-5,5 -bis-l,2,4-triazole-3- mercaptans, is carried out in a manner analogous to the preparation of 5-substituted l,2,4-triazole-3-mercaptans. The corresponding carboxylic acid esters which are used as starting materials, are cyclized with thiosemicarbazides or thiocarbohydrazide (Pesson, Dupin and Polmans, Bull. Soc. Chim. France (5) 1581 (1961)).

The preparation of Compound 14 is described in the following in detail:

Ninety-one grams of thiosemicarbazide and 89 g. of dimethylthiodiglycollate are added to a solution of 23 g. of sodium dissolved in 2 liters of ethanol. The reaction mixture is refluxed for 12 hours. After cooling, it is suction-filtered and the filtrate is concentrated by evaporation. The combined residues are dissolved in water and the reaction product is precipitated by the introduction of carbonic acid. Sixty grams of bis[3-mercapto-1,2,4-triazolyl-(5)-methyl]-sulfide are obtained.

The other compounds given in the table are obtained by similar processes.

The antibronzing agents are preferably added to the lightsensitive silver halide emulsion layer. They may be added to the emulsion, preferably after the chemical ripening, or to the 25 finished casting solution. The compounds are preferably used in solution in a suitable solvent such as water, alcohol, dimethylformamide or in an equivalent quantity of aqueous alkali.

The amount of the antibronzing agent is not critical and de- 0 pends on the type of the silver halide emulsion or the effects desired. In general quantities of 1/50th to 1/ 1,000th of a mol per mol of silver halide, preferably 1/ 100 to 1/500th mol per mol of silver halide, that is 0.1-5 g., preferably 0.5-2.5 g. per mol of silver halide have proved sufficient.

3 The compounds may also be added to auxiliary waterpermeable layers of the photographic material, e.g., to the baryta coating or to a protective layer. The antibronzing agents of the invention may be added to any of the conventional silver halide emulsions. Examples of suitable silver halides are silver chloride, silver bromide or mixtures of the haby other film-forming natural or synthetic polymers. Suitable agents for this purpose are, e.g., alginic acid and its derivatives such as its salts, esters or amides, carboxymethyl cellulose, alkyl cellulose, starch and starch derivatives, polyvinyl alcohol, copolymers with vinyl alcohol and vinyl acetate units,

polyvinyl pyrrolidone and the like.

The silver halide emulsion may contain any known additives, such as antifogging agents, stabilizers, hardeners, plasticizers and wetting agents. The emulsion may also be both chemically and spectrally sensitized. It can be chemically sensitized by carrying out the ripening in the presence of small quantities of sulfur containing compounds, such as allyl isothiocyanate, allylthioether or sodium thiosulfate. The lightsensitive silver halide emulsion may also be sensitized with reducing agents, e.g., with the tin compounds described in Belgian Pat. Nos. 493,464 and 568,687; the imino-aminomethanesulfinic acid compounds described in Belgian Pat. No. 547,323 or with small quantities of noble metal compounds such as compounds of gold, platinum, palladium, iridium, ruthenium and rhodium. The emulsions may also be sensitized with polyalkylene oxide derivatives, e.g., with polyethylene oxide having a molecular weight of between 1,000 and 20,000, with condensation products of alkylene oxides and aliphatic alcohols, glycols and cyclic dehydration products of hexitols, with alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diarnines and amides. These condensation products should have a molecular weight of at least 700, preferably more than 1,000. These sensitizers may, of course be combined in order to achieve particular effects, as is described in Belgian Pat. No. 537,278 and in British Pat. No. 727,982.

Instead of incorporating the antibronzing agents in the photographic copying material, they may be dissolved in one of the treatment baths. For example, they may be added to the developer, the fixing bath, or to an additional hardening bath or a bath which contains surface active compounds and which is used as the final treatment bath before the image containing material is dried at elevated temperature. The compounds according to the invention are generally dissolved in the bath as alkali metal salts in concentrations which may vary within very wide limits but generally lie between and 100 mg. per liter, provided that the compounds are soluble in the fixing bath. Satisfactory results are obtained using, for example, to 50 mg. per liter of the compounds in the developer bath or in the fixing bath. When the photographic copying material is passed through such a bath, the water permeable layers take up a certain amount of the antibronzing agent.

EXAMPLE 1 A silver chlorobromide gelatin emulsion (20 mols percent of AgBr) which is unwashed and which contains per liter 0.18 mol of silver halide, 2 ml. of a 1 percent alcoholic solution of 1-pheny1-5-mercaptotetrazole, 20 ml. of a 10 percent aqueous saponin solution and 2 ml. of a 30 percent aqueous formalin solution is divided into eight portions. To each portion is added an antibronzing agent of the present invention. Details are given in the following table.

The emulsions are applied onto a barytacoated paper support. The final dried layer contains 1.6 g. silver per square meter in the form of silver halide.

Comparison strips of the photographic material thus obtalned is exposed in a sensitometer customarily employed in the art. The exposed samples are developed in a developer of the following composition (temperature 18 C., developing time 90 seconds): 1

l g. of p-methylaminophenol 3 g. of hydroquinone 13 g. of anhydrous sodium sulfite 26 g. of anhydrous sodium carbonate 1 g. of potassium bromide dissolved in water and made up to 1,000 ml. The developed material is fixed for 10 minutes in an aqueous solution of sodium thiosulfate and rinsed.

The moist material is dried on a high-gloss press heated to 130 C. Whereas the high-gloss drying causes a color change from brown to greenish brown to blue in the control sample (without addition), the brown image tones do not change if a compound according to the invention is present. The maximum density of the different materials is determined with a densitometer of an air-dried sample as compared with a material dried on a glazing press. The following results are obtained;

TABLE 2 Maximum Density from Concentration Table 1 mgjkg. Air dried glazing press Control sample 0 2.30 1.72 1 166 2.28 2.33 3 238 2.31 2.43 5 166 2.28 2.40 6 182 2.33 2.41 7 254 2.32 2.42 8 21 1 2.35 2.39 9 185 2.31 2.30 14 2.29 2.33

EXAMPLE 2 A silver chloride emulsion which contains per liter 0.18 mol of silver chloride and the additives mentioned in Example 1 is divided into several portions. To each portions is added an antibronzing agent according to the invention as referred to in detail in the following Table 3. The compounds are added in the form of a solution in dimethylformamide as described in Example 1.

The emulsions are applied onto a barytacoated paper support. The dried layer contains 1.35 g. silver in the form of silver chloride per square meter.

Further processing is accomplished as described in Example Comparison strips of the photographic material of the control sample of Example 1 are processed as described in Example l but using developers that contain an antibronzing agent of the present invention in the amount indicated in the following table. The following results are obtained:

TABLE 4 No. of Maximum Density compound Concentration Air dried on glafrom Table 1 rngJl. dried zing press Control sample 2.24 1.78 1 22 2.24 2.27 2 26 2.24 2.31 3 32 2.24 2.36 4 45 2.24 2.41 5 44 2.24 2.42 6 24 2.24 2.34 7 34 2.24 2.37 8 28 2.24 2.33 9 49 2.24 2.37 10 42 2.24 2.37 14 20 2.24 2.15 15 40 2.24' 2.31

Whereas the high-gloss drying produces a change from warm brown to a color varying from greenish brown to blue in the control sample, the warm brown image tone remains unchanged when developed in a developer containing the antibronzing agent.

EXAMPLE 4 TABLE 5 No. of Maximum density compound Concentration Air dried on glafrom Table l mgJl. dried zing press Control sample 0 2.24 1.78 1 2.24 2.34 2 20 2.24 2.43 9 20 2.24 2.34 [0 20 2.24 2.41

Whereas high-gloss drying causes a color change from warm brown to greenish brown and then to blue in the control sample, the warm brown image tones do not change if fixing is performed in the presence of the antibronzing agent.

We claim:

1. In a process for the production of photographic images by exposing a supported silver halide emulsion layer, developing, fixing and hot drying, the improvement consisting of hot drying, the silver image in contact with an antibronzing amount of a compound of the following formula or its tautomeric 3- thione form:

\F T H S III III --HS H R R wherein:

R is hydrogen, a saturated or olefinically unsaturated aliphatic group having up to six carbon atoms, a radical of the phenyl series or an amino group, and

X is an interrupted chain of two to 10 hydrocarbon groups,

each interruption consisting of O, S, NH or S0 2. A process as defined in claim 1, wherein the hydrocarbon groups are methylene groups, the number of such groups is not more than six, and the interruptions are oxygen, sulfur or sulfonyl groups.

3. A photographic element containing at least one light-sensitive silver halide emulsion layer and an antibronzing amount of a compound of the following formula or its tautomeric 3- thione form:

wherein:

R is hydrogen, a saturated or olefinically unsaturated aliphatic group having up to six carbon atoms, a radical of the phenyl series or art amino groulp, and X 18 an interrupted chain of two to 0 hydrocarbon groups,

each interruption consisting of O, S, Nl-l or S0,.

4. A material of claim 3 wherein the hydrocarbon groups are methylene groups, the number of such groups is not more than six, and the interruptions are oxygen, sulfur or sulfonyl groups.

5. An aqueous photographic developer composition containing photographic developer and an antibronzing amount of a compound of the following formula or its tautomeric 3- thione form:

wherein:

R is hydrogen, a saturated or olefinically unsaturated aliphatic group having up to six carbon atoms, a radical of the phenyl series or an amino group, and

X is an interrupted chain of two to 10 hydrocarbon groups,

each interruption consisting of O, S, NH or S0,.

6. The developer composition of claim 5 wherein the hydrocarbon groups are methylene groups, the number of such groups is not over six, and the interruptions are oxygen, sulfur or sulfonyl groups.

7. A photographic fixing bath containing a silver halide solvent and an antibronzing amount of a compound of the following formula or its tautomeric 3-thione form: 

2. A process as defined in claim 1, wherein the hydrocarbon groups are methylene groups, the number of such groups is not more than six, and the interruptions are oxygen, sulfur or sulfonyl groups.
 3. A photographic element containing at least one light-sensitive silver halide emulsion layer and an antibronzing amount of a compound of the following formula or its tautomeric 3-thione form: wherein: R is hydrogen, a saturated or olefinically unsaturated aliphatic group having up to six carbon atoms, a radical of the phenyl series or an amino group, and X is an interrupted chain of two to 10 hydrocarbon groups, each interruption consisting of O, S, -NH- or SO2.
 4. A material of claim 3 wherein the hydrocarbon groups are methylene groups, the number of such groups is not more than six, and the interruptions are oxygen, sulfur or sulfonyl groups.
 5. An aqueous photographic developer composition containing photographic developer and an antibronzing amount of a compound of the following formula or its tautomeric 3-thione form: wherein: R is hydrogen, a saturated or olefinically unsaturated aliphatic group having up to six carbon atoms, a radical of the phenyl series or an amino group, and X is an interrupted chain of two to 10 hydrocarbon groups, each interruption consisting of O, S, -NH- or SO2.
 6. The developer composition of claim 5 wherein the hydrocarbon groups are methylene groups, the number of such groups is not over six, and the interruptions are oxygen, sulfur or sulfonyl groups.
 7. A photographic fixing bath containing a silver halide solvent and an antibronzing amount of a compound of the following formula or its tautomeric 3-thione form: wherein: R is hydrogen, a saturated or olefinically unsaturated aliphatic group having up to six carbon atoms, a radical of the phenyl seris or an amino group, and X is an interrupted chain of two to 10 hydrocarbon groups, each interruption consisting of O, S, -NH- or SO2.
 8. The fixing bath of claim 7 wherein the hydrocarbon groups are methylene groups, the number of such groups is not more than six, and the interruptions are oxygen, sulfur or sulfonyl groups. 